Reversibility of spermine-induced intestinal maturation in the rat.

In the present investigation, the reversibility of spermine-induced precocious intestinal maturation was studied. Neonatal rats received either saline or spermine (4 mumol, twice daily) solution orally on the 11th and 12th postnatal day. They were killed on the 13th, 14th, 15th, 16th, and 17th postnatal days. After the small bowel was removed, it was either divided into three equal parts or prepared for electrophoretic analysis. Histological examination, protein content measurement, and disaccharidase activity estimation were performed on each part of the intestine. Spermine administration was shown to induce structural and mucosal enzyme changes characteristic of postnatal maturation. This phenomenon, which was generally clearly observed in 13- and 14-day-old rats, then became less apparent in 15- and 16-day-old animals. Differences were noted according to the segment of intestine or the biochemical parameter analyzed. When rats were 17 days old, no significant differences generally existed between control and spermine-treated rats. If the 140- to 150-kDa proteins, isolated by electrophoresis, are assumed to represent the subunits of the sucrase-isomaltase complex, the results obtained indicate that spermine induces a modification of the concentration of this complex. When compared to values obtained in adult rats, the concentration of the complex was approximately three times higher in spermine-treated 13-day-old rats, while no differences were found in spermine-treated 14-day-old rats. Further, similar concentrations were found in control and spermine-treated rats with an age of 17 days. These results suggest that spermine-induced precocious intestinal maturation is reversible when spermine treatment is stopped.